1. Field of the Invention
The present invention relates to novel, transient prodrug derivatives of dopa, including levodopa, and dopamine, and, more especially, relates to certain acyl-X-methylether latentiated forms of such sympathomimetic amines.
As employed in this application, the expression "prodrug" denotes a derivative of a known and proven prior art compound, which derivative, when absorbed into the bloodstream of a warm-blooded animal, "cleaves" in such a manner as to release the proven drug form and permits the same to attain a higher bioavailability level than that which could be obtained if the proven drug form, per se, was administered.
Furthermore, also as used in this application, the term "transient" denotes "cleavage" of the compounds of this invention in such a manner that the proven drug form is released and the remaining "cleaved" moiety is non-toxic and metabolized in such a manner that non-toxic, metabolic products are produced.
2. Description of the Prior Art:
It is well known to this art that dopa, L-dopa and dopamine, and their salts, are useful active agents for the treatment or management of a wide variety of disease states or conditions, e.g., same are useful anticholinergic agents, antiparkinsonian agents, adrenergic agents, cardiotonic agents, and the like. See generally Cutting's Handbook of Pharmacology, 41, "Sympathetic Stimulants or Adrenergic Agents", pp. 436-455, Sixth Edition (1979); The Merck Index, pp. 3424 & 5314, Ninth Edition (1976).
Nevertheless, it too is well known to the art that such sympathomimetic amines, and the various art-recognized therapeutically active derivatives thereof, are characterized by certain inherent disadvantages, notably serious bioavailability and physiological availability problems upon administration. Such reduced availability can be attributed in part to poor lipid solubility [by reason of the presence of the hydrophilic phenolic hydroxyl groups], and also to metabolic losses during and following conventional administration. Other disadvantages associated with the prior art compounds are instability to both air and light, and same are subject to chemical attack by many agents that are conventionally used in pharmaceutical preparations, as well as a variety of other unfavorable pharmacodynamic properties. Also, for certain applications, relatively high concentrations of drug are required.
Thus, there exists a clear and present need for novel latentiated forms of dopa and dopamine, which derivatives would be conspicuously devoid of those disadvantages and drawbacks that to date have characterized the prior art compounds.